I'm currently on Toad for Oracle 18.104.22.168.
Since recently I've been having problems with existing sources for a.o. triggers: blank lines in the declaration section are causing compiles to fail. Also, these blank lines are marked invalid by Toad. My DBA assures me there have been no recent fixes.
So I retried using Toad 12.8 - no problem at all, compiles just fine with the blank lines in place.
Please see attachment for a screen shot of the 22.214.171.124 showing syntax error after first blank line in declaration section of trigger: